Plant photosynthesis and biomass production are associated with the amount of intercepted light, especially the light distribution inside the canopy. Three virtual canopies (n = 80, 3.25 plants/m2) were constructed based on average leaf size of the digitized plant structures: ‘small leaf’ (98.1 cm2), ‘medium leaf’ (163.0 cm2) and ‘big leaf’ (241.6 cm2). The ratios of diffuse light were set in three gradients (27.8%, 48.7%, 89.6%). The simulations of light interception were conducted under different ratios of diffuse light, before and after the normalization of incident radiation. With 226.1% more diffuse light, the result of light interception could increase by 34.4%. However, the 56.8% of reduced radiation caused by the increased proportion of diffuse light inhibited the advantage of diffuse light in terms of a 26.8% reduction in light interception. The big-leaf canopy had more mutual shading effects, but its larger leaf area intercepted 56.2% more light than the small-leaf canopy under the same light conditions. The small-leaf canopy showed higher efficiency in light penetration and higher light interception per unit of leaf area. The study implied the 3D structural model, an effective tool for quantitative analysis of the interaction between light and plant canopy structure.
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The increased cultivation of highly productive C4 crop plants may contribute to a second green revolution in agriculture. However, the regulation of mineral nutrition is rather poorly understood in C4 plants. To understand the impact of C4 photosynthesis on the regulation of sulfate uptake by the root and sulfate assimilation into cysteine at the whole plant level, seedlings of the monocot C4 plant maize (Zea mays) were exposed to a non-toxic level of 1.0 µl l−1 atmospheric H2S at sulfate-sufficient and sulfate-deprived conditions. Sulfate deprivation not only affected growth and the levels of sulfur- and nitrogen-containing compounds, but it also enhanced the expression and activity of the sulfate transporters in the root and the expression and activity of APS reductase (APR) in the root and shoot. H2S exposure alleviated the establishment of sulfur deprivation symptoms and seedlings switched, at least partly, from sulfate to H2S as sulfur source. Moreover, H2S exposure resulted in a downregulation of the expression and activity of APR in both shoot and root, though it hardly affected that of the sulfate transporters in the root. These results indicate that maize seedlings respond similarly to sulfate deprivation and atmospheric H2S exposure as C3 monocots, implying that C4 photosynthesis in maize is not associated with a distinct whole plant regulation of sulfate uptake and assimilation into cysteine.
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In een city farm optimaliseren we alle factoren voor zover we dat met de huidige stand van techniek kunnen. Relatief goedkoop is het regelen van de temperatuur, de luchtvochtigheid en het CO2-gehalte. Relatief duur is het aanbieden van de meeste efficiënte lichtkleuren in de optimale mix voor de hoogste productie en de beste kwaliteit. In het algemeen werken we met blauw licht voor o.a. opening van de huidmondjes, rood licht als belangrijkste fotosynthesekleur en verrood licht voor het extra bevorderen van de foto-synthese en sturen van het plantmodel. Soms werken we met rode en witte LED-lampen, waarbij de witte lampen zorgen voor blauw en o.a. groen licht en het mogelijk maken de kleuren weer normaal te zien.
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The need of an adaptive sustainable solution for the increased land scarcity, growing urbanization, climate change and flood risks resulted in the concept of the floating urbanization. In The Netherlands this new type of housing attracted the interest of local authorities, municipalities and water boards. Moreover, plans to incorporate floating houses in the urban planning have already been developed. However, the knowledge gap regarding the potential effect on the water quality halts the further development of the floating houses. This paper shows the results of a water quality measurement campaign, as part of the national program “Knowledge for climate”, at a small floating houses project in Delft and serves as a case study for addressing the environmental-ecological knowledge gap on this topic.
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The need of an adaptive sustainable solution for the increased land scarcity, growing urbanization, climate change and flood risks resulted in the concept of the floating urbanization. In The Netherlands this new type of housing attracted the interest of local authorities, municipalities and water boards. Moreover, plans to incorporate floating houses in the urban planning have already been developed. However, the knowledge gap regarding the potential effect on the water quality halts the further development of the floating houses. This paper shows the results of a water quality measurement campaign, as part of the national program “Knowledge for climate”, at a small floating houses project in Delft and serves as a case study for addressing the environmental-ecological knowledge gap on this topic.
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Semi-closed greenhouses have been developed in which window ventilation is minimized due to active cooling, enabling enhanced CO2 concentrations at high irradiance. Cooled and dehumidified air is blown into the greenhouse from below or above the canopy. Cooling below the canopy may induce vertical temperature gradients along the length of the plants. Our first aim was to analyze the effect of the positioning of the inlet of cooled and dehumidified air on the magnitudes of vertical temperature and VPD gradients in the semi-closed greenhouses. The second aim was to investigate the effects of vertical temperature gradients on assimilate production, partitioning, and fruit growth. Tomato crops were grown year-round in four semiclosed greenhouses with cooled and dehumidified air blown into the greenhouses from below or above the crop. Cooling below the canopy induced vertical temperature and VPD gradients. The temperature at the top of the canopy was over 5°C higher than at the bottom, when outside solar radiation was high (solar radiation >250 J cm-2 h-1). Total dry matter production was not affected by the location of the cooling (4.64 and 4.80 kg m-2 with cooling from above and from below, respectively). Percentage dry matter partitioning to the fruits was 74% in both treatments. Average over the whole growing season the fresh fruit weight of the harvested fruits was not affected by the location of cooling (118 vs 112 g fruit-1). However, during summer period the average fresh fruit weight of the harvested fruits in the greenhouse with cooling from below was higher than in the greenhouse with cooling from above (124 vs 115 g fruit-1).
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Nieuw-Zeelandse spinazie is een kansrijk gewas voor de teelt op brak (grond)water of op verzilte gronden. Deze teelthandleiding bevat informatie voor telers die geïnteresseerd zijn om met het gewas aan de slag te gaan. Nieuw-Zeelandse spinazie, zilte teelt, proeftuin, landbouw meerdere smaken
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The sensitivity of tropical forest carbon to climate is a key uncertainty in predicting global climate change. Although short-term drying and warming are known to affect forests, it is unknown if such effects translate into long-term responses. Here, we analyze 590 permanent plots measured across the tropics to derive the equilibrium climate controls on forest carbon. Maximum temperature is the most important predictor of aboveground biomass (−9.1 megagrams of carbon per hectare per degree Celsius), primarily by reducing woody productivity, and has a greater impact per °C in the hottest forests (>32.2°C). Our results nevertheless reveal greater thermal resilience than observations of short-term variation imply. To realize the long-term climate adaptation potential of tropical forests requires both protecting them and stabilizing Earth’s climate.
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Large floating projects have the potential to overcome the challenge of land scarcity in urban areas and offer opportunities for energy and food production, or even for creating sustainable living environments. However, they influence the physical, chemical, biological and ecological characteristics of water bodies. The interaction of the floating platforms affect multiple complex aquatic processes, and the potential (negative/positive) effects are not yet fully understood. Managing entities currently struggle with lack of data and knowledge that can support adequate legislation to regulate future projects.In the Netherlands the development of small scale floating projects is already present for some years (e.g. floating houses, restaurants, houseboats), and more recently several large scale floating photovoltaic plants (FPV) have been realized. Several floating constructions in the Netherlands were considered as case-studies for a data-collection campaign.To obtain data and images from underneath floating buildings, underwater drones were equipped with cameras and sensors. The drones were used in multiple locations to scan for differences in concentrations of basic water quality parameters (e.g. dissolved oxygen, electrical conductivity, algae, light intensity) from underneath/near the floating structures, which were then compared with data from locations far from the influence of the buildings. Continuous data was also collected over several days using multi-parameter water quality sensors permanently installed under floating structures.
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Wind and solar power generation will continue to grow in the energy supply of the future, but its inherent variability (intermittency) requires appropriate energy systems for storing and using power. Storage of possibly temporary excess of power as methane from hydrogen gas and carbon dioxide is a promising option. With electrolysis hydrogen gas can be generated from (renewable) power. The combination of such hydrogen with carbon dioxide results in the energy carrier methane that can be handled well and may may serve as carbon feedstock of the future. Biogas from biomass delivers both methane and carbon dioxide. Anaerobic microorganisms can make additional methane from hydrogen and carbon dioxide in a biomethanation process that compares favourably with its chemical counterpart. Biomethanation for renewable power storage and use makes appropriate use of the existing infrastructure and knowledge base for natural gas. Addition of hydrogen to a dedicated biogas reactor after fermentation optimizes the biomethanation conditions and gives maximum flexibility. The low water solubility of hydrogen gas limits the methane production rate. The use of hollow fibers, nano-bubbles or better-tailored methane-forming microorganisms may overcome this bottleneck. Analyses of patent applications on biomethanation suggest a lot of freedom to operate. Assessment of biomethanation for economic feasibility and environmental value is extremely challenging and will require future data and experiences. Currently biomethanation is not yet economically feasible, but this may be different in the energy systems of the near future.
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